1. Field of the Invention
The invention relates generally to collection devices and, more particularly, to vacuum operated and at least partially disposable collection devices.
Still more particularly, the invention relates to collection devices including a flexible bag or liner which is supported by a canister cover and located within a rigid canister connected to the canister cover.
2. Reference to the Prior Art
In the past, liners or bags have been secured to a canister cover by heat sealing and/or by the use of a heat sealant. Bags or liners made from a plasticized flexible polyvinylchloride can be welded by using electrodes and a radio frequency electrical supply. When a flexible bag or liner is composed of polyethylene it can be welded or fused to a stiffer polyethylene canister cover by using a heated electrode.
Whatever materials have been used in the past to manufacture the bag or liner and the canister cover, all such products have relied on fusing the bag or liner to the canister cover. Furthermore, and in order to facilitate such fusing, both the bag or liner and the canister cover have been made from compatible materials, for example, flexible polyvinylchloride to rigid polyvinylchloride, or low-density polyethylene to high-density polyethylene. In all cases, uniform and controlled pressure has to be applied at the point of attachment of the bag or liner to the canister cover. In addition, the energy applied, whether resistance or radio frequency current, has to be accurately controlled, as does the duration of its application. Fluctuations in these conditions can lead to missed areas or weak areas of fusion when the heat, pressure, or duration is insufficient, or the electrode may push through the wall of the thin bag or liner when the heat, pressure, or duration is excessive. Suffice to say that the process of fusing the two parts together is such as to lead to a percentage of rejects and to frequent testing to ensure that conditions are optimum.
Any product requiring two parts to be fused together must employ parts of compatible material. Such compatibility requirements would have to take precedence over optimum performance for each part. While flexible plasticized polyvinylchloride not only affords crystal clarity but great flexibility, properties very desirable in a bag or liner, such material cannot be fused to a high-density polyethylene canister cover whose properties most suit the performance of the canister cover.
Attention is directed to U.S. Pat. No. 3,680,560 dated Aug. 1, 1972.